Hygiene tissues such as wet or moist towelette, also known as a wet nap, wet towel, or a wet wipe, are usually a small moistened piece of paper or cloth that often comes folded and individually wrapped for convenience. These are used for personal hygiene, cleaning or household cleaning.
Typically, the base material is produced as air-laid paper where the fibers are carried and formed to the structure of paper by air. Manufacturing technologies include wet laid non-wovens, melt spinning webs, dry laid webs, needled felts and others. Each of these technologies may be used alone or in composite structures. These products are available in multiple fiber chemistries (cotton, wood pulp, polyester, polypropylene, nylon, etc.) and with multiple physical characteristics, further broadening the available choices.
They are moistened with water or other liquids like isopropyl alcohol depending on the applications. The paper might be treated with softeners, lotions or added perfume to get the right properties or “feeling”. Air-laid paper is very bulky, porous and soft compared with normal wet-laid paper and tissue. It has good water absorption properties and is much stronger compared with normal tissue, which also makes it difficult to flush as it does not disintegrate easily, but instead may clog the sewage system.
The main characteristics for this air laid paper are that it's soft, does not scratch, it's non-linting, i.e. no dust, not static, it's strong, even when wet, and can thus be rinsed and reused. Further the material is clean, hygienic, and can be sterilized. It has a textile-like surface and drape and it can be dyed, printed, embossed, coated and made solvent resistant. There are two dry aid nonwoven methods: carding and air laid. Carding is a well-established method of forming nonwoven textile materials. Fibers are separated and aligned while going through a system of cards before being sent directly to or through a cross-lapper to a bonding technique. In air laying, an air stream is used as the vehicle for short fibers. The fibers are collected on a moving belt or perforated drum where they form a randomly oriented web. Typically, air laid webs have a lower density and higher softness than carded webs. Air laid webs offer great versatility in terms of the fibers and fiber blends that can be used. HVAC is one application where air laid materials are common.
Air-laid paper does, however, not use water as the carrying medium for the fiber, like in a normal papermaking process. Fibers are carried and formed to the structure of paper by air. The air-laid structure is isotropic. The raw material is typically long fibered softwood fluff pulp in roll form. The pulp is defibrated in a hammer mill. Defibration is the process of freeing the fibers from each other before entering the paper machine. Important parameters for dry defibration are shredding energy and knot content. Normally an air-laid paper consists of about 85% fiber. A binder must be applied as a spray or foam. Alternatively, additional fibers or powders can be added to the pulp which can then be activated and cured by heat.
Wet wipes can serve a number of household purposes such as baby wipes which may be saturated with solutions anywhere from gentle cleansing ingredients to alcohol based ‘cleaners’. Of course there is a negative environmental aspect to these wet wipes in that they are usually not biodegradable, other options such as using cotton or terry cloth type of wipes involves using large amounts of water, and washing the cloth regularly. There is thus a need for a “greener” alternative.
A new concern with traditional wet wipes is also that they may in fact cause rashes, and an additive used as a preservative called methylchloroisothiazolinone or MCI has been pointed out as a cause of particular concern, in a study made by Mayo Clinic in Rochester, Minn. There is thus also a need for a wet wipe not using preservatives, which can in any way be harmful to the environment.
Today one can find even wet wipes for pet care, and of course for washing hands before or after a meal, or for other hygiene reasons. Also in toilettes is the use of wet wipes quite common.
Other types of hygiene tissues may include cleansing pads, which essentially are fiber sponges which have been previously soaked with water, alcohol and other active ingredients for a specific intended use. They are ready to use hygiene products and they are simple and convenient solutions to dispose of dirt or other undesirable elements. There are different types of cleansing pads offered by the beauty industry: make-up removing pads, anti-spot treatments and anti-acne pads that usually contain salicylic acid, vitamins, menthol and other treatments). Cleansing pads for preventing infection are usually saturated with alcohol and bundled in sterile package. Hands and instrument may be disinfected with these pads while treating wounds. Further to this there are also pain relief pads sopping with alcohol and benzocaine. These pads are good for treating minor scrapes, burns, and insect bites. They disinfect the injury and also ease pain and itching.
The issue of disposability of products is of great concern to the nonwovens industry. Landfills, incineration, multiple sewage treatment and residential septic systems are among the common choices for nonwoven product disposal today. Products targeted for the latter disposal routes, via residential and commercial toilets, are termed flushable. Current flushable products have limitations.
Dry products, such as bathroom tissue, have been designed with minimal wet strength so that the tissue can disintegrate under the agitation in the plumbing systems. They are not designed for applications where water will be encountered in use. Flushable wet wipes have high wet strengths and do not lose their strength upon disposal. These products remain intact and identifiable in the disposal system. Further there is a relatively high production costs involved in manufacturing conventional wet toweletes/wipes, and the air laid webs are usually bound with expensive binders. These conventional wet wipes also dry quickly when exposed to air, and are usually not biodegradable.